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| author | Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> | 2018-05-01 18:20:39 +0000 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 2018-05-01 12:20:39 -0600 |
| commit | 41e2c1b0b4effb21729299c5dd7b3b2abd03d87b (patch) | |
| tree | dbf282b7ccf2c09ed3ae8e666850c2bbf601db30 /gcc/vr-values.c | |
| parent | 1a142d6e6858e6fb58bab8592ee1223621867f1e (diff) | |
| download | gcc-41e2c1b0b4effb21729299c5dd7b3b2abd03d87b.tar.gz | |
re PR tree-optimization/82665 (missing value range optimization for memchr)
PR tree-optimization/82665
* vr-values.c (vr_values::extract_range_from_binary_expr): Handle
pointer subtraction where arguments come from a memchr call.
PR tree-optimization/82665
* gcc.dg/tree-ssa/pr82665.c: New test.
From-SVN: r259806
Diffstat (limited to 'gcc/vr-values.c')
| -rw-r--r-- | gcc/vr-values.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/gcc/vr-values.c b/gcc/vr-values.c index b1f587d2b92..74f813e7334 100644 --- a/gcc/vr-values.c +++ b/gcc/vr-values.c @@ -793,6 +793,39 @@ vr_values::extract_range_from_binary_expr (value_range *vr, extract_range_from_binary_expr_1 (vr, code, expr_type, &vr0, &vr1); + /* Set value_range for n in following sequence: + def = __builtin_memchr (arg, 0, sz) + n = def - arg + Here the range for n can be set to [0, PTRDIFF_MAX - 1]. */ + + if (vr->type == VR_VARYING + && code == POINTER_DIFF_EXPR + && TREE_CODE (op0) == SSA_NAME + && TREE_CODE (op1) == SSA_NAME) + { + tree op0_ptype = TREE_TYPE (TREE_TYPE (op0)); + tree op1_ptype = TREE_TYPE (TREE_TYPE (op1)); + gcall *call_stmt = NULL; + + if (TYPE_MODE (op0_ptype) == TYPE_MODE (char_type_node) + && TYPE_PRECISION (op0_ptype) == TYPE_PRECISION (char_type_node) + && TYPE_MODE (op1_ptype) == TYPE_MODE (char_type_node) + && TYPE_PRECISION (op1_ptype) == TYPE_PRECISION (char_type_node) + && (call_stmt = dyn_cast<gcall *>(SSA_NAME_DEF_STMT (op0))) + && gimple_call_builtin_p (call_stmt, BUILT_IN_MEMCHR) + && operand_equal_p (op0, gimple_call_lhs (call_stmt), 0) + && operand_equal_p (op1, gimple_call_arg (call_stmt, 0), 0) + && integer_zerop (gimple_call_arg (call_stmt, 1))) + { + tree max = vrp_val_max (ptrdiff_type_node); + wide_int wmax = wi::to_wide (max, TYPE_PRECISION (TREE_TYPE (max))); + tree range_min = build_zero_cst (expr_type); + tree range_max = wide_int_to_tree (expr_type, wmax - 1); + set_value_range (vr, VR_RANGE, range_min, range_max, NULL); + return; + } + } + /* Try harder for PLUS and MINUS if the range of one operand is symbolic and based on the other operand, for example if it was deduced from a symbolic comparison. When a bound of the range of the first operand |